Why do we provide transverse reinforcement in beams?

Transverse reinforcement in beams is provided mainly to resist the shear forces or forces which act in a direction perpendicular to the longitudinal direction of reinforced concrete beams. We follow IS - 456:2000 design procedure to calculate the reinforcement required for resisting shear force. Most commonly use stirrups as transverse reinforcement. As you all know that the maximum value of shear force is obtained at the support location and it reduces as we move towards the middle of the section.

In a reinforced concrete structure both steel and concrete take part actively in resisting the shear force. So the total shear strength of the concrete section is the sum of shear strength of concrete and shear strength of reinforcement.

Transverse reinforcement

Transverse reinforcement or shear reinforcement can be provided in multiple ways . One of the most commonly used method is by providing stirrups as hoops covering the longitudinal reinforcement. Sometimes the longitudinal reinforcement is bent towards upward. Mostly in support areas, where bending is not a major cause for failure.

Design of Shear reinforcement as per IS 456: 2000

Step 1: Compute the value of equivalent shear force in the section. It is a function of the actual shear force and force due to the torsional moment.

$$V_e = V_u + 1.6(\frac{T_u}{b})$$

Where,

Ve is the equivalent shear

Vu is the shear force

Tu is the torsional moment

b is the breadth of cross section.

Step 2: Compute the value of equivalent shear stress using the formula:

$$\tau_{\mathrm{ve}}=\left(\mathrm{V}_{\mathrm{e}} / \mathrm{bd}\right)$$

Then check the value of equivalent shear stress, it should not exceed the value of critical shear stress (Table 20 IS 456: 2000).

Step 3: Provide minimum reinforcement as shear reinforcement as per clause 26.5.1.6. of IS :456:2000.

You can check this post to know about different beam sections.